Optical transceivers typically have no direct external indication as to the speed capability of the unit, and have no display mechanism to indicate whether the unit is defective. With regard to speed capability, various units from the same manufacturer may appear identical or nearly so, and the only way to differentiate between, for example, a 2 Gb (gigabyte) transceiver and a 4 Gb transceiver, is to have the two different part numbers memorized. With regard to viability, one method to make a determination whether a transceiver is viable is to exchange a suspect transceiver with a known good one and try communication using the known good transceiver.